New Design Approach of Compound Helicopter PRASETYO EDI, NUKMAN YUSOFF and AZNIJAR AHMAD YAZID Department of Engineering Design & Manufacture, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, MALAYSIA p_edi@um.edu.my http://design-manufacturer.eng.um.edu.my/ CATUR SETYAWAN K., NURKAS W., and SUYONO W. A. Directorate of Technology Indonesian Aerospace (IAe) Jl. Pajajaran 154, Bandung Indonesia catursk@yahoo.com http://www.indonesian-aerospace.com/index.php Abstract: - Current trends in the design of helicopter have shown that in order to be economically viable and competitive it is necessary to investigate new design concept which may give an improvement in performance and operational flexibility goal and expanding the flight envelope of rotorcraft, but must be shown to be cost- effective. The helicopter has carved a niche for itself as an efficient vertical take-off and landing aircraft, but have limitation on its cruising speed due to restrictions of retreating blade stall and advancing blade compressibility on the rotor in edgewise flight. This is a challenging task, which might be solved by the use of new design approach. It is believed that the application of a compound helicopter design concept would assist in achieving such a task. This paper describes an investigation aimed to examine the suitability of a compound helicopter design concept, allowing for the use of a combined conventional fix-wing aircraft with single propeller in the nose and conventional helicopter to satisfy the above objectives. The paper describes the phenomenon of presents VTOL (vertical take-off and landing) aircraft. It then discusses the benefits and penalties of the presents concept. Description is then given of the concept proposed compound helicopter which incorporated combines main rotor-wing-auxiliary propeller. It concludes with a discussion of the results and recommendations for future work. Key-Words: - compound helicopter, VTOL (vertical take-off and landing), high speed helicopter, aircraft design 1 Introduction The operational benefits of an ability to take off and landing vertically are self-evident. Conventional aircraft must operate from a relatively small number of airports or airbases with long paved runways. For commercial transportation, the airport is rarely where you actually wish to go, and is usually crowded, causing delays in the air and on the ground. The military airbases is highly vulnerable to attack, and during a wartime situation the time expended cruising to and from the in-the-rear airbase increase the required aircraft range and also increases the amount of time it takes for the aircraft to respond to a call for support. The first type of VTOL heavier than air aircraft was the helicopter, whish was conceived by Leonardo da Vinci but not regularly used until shortly after World War II. The Helicopter rapidly proved its worth for rescue operations and short- range point-to-point transportation, but its inherent speed and range limitations restricted its application. VTOL refers to a capability for Vertical Take Off and landing, as opposed to Conventional Take Off and Landing (CTOL). An aircraft, which has the flexibility to perform either vertical or short take off landings, is said to have Vertical or Short Take off and Landing (VSTOL) capability. An aircraft that has insufficient lift for vertical flight at take off weight but which can land vertically at landing weight is called a Sort Take off and Vertical Landing (STOVL). Table 1 [1] shows the Methods of Transition for Various V/STOL Concepts. This table also shows there are two fundamental problems stand out because they tend to have greatest impact upon the WSEAS TRANSACTIONS on APPLIED and THEORETICAL MECHANICS Prasetyo Edi, Nukman Yusoff, Aznijar Ahmad Yazid, Catur Setyawan K., Nurkas W., Suyono W. A. ISSN: 1991-8747 799 Issue 9, Volume 3, September 2008